Steel: 31CrV3 47-52 HRC Chromed H: 25 mm Length: 95 mm An angle hex key (also known as an "Allen key") is used for working with fasteners that have an internal hexagonal shape. Angle keys have two levers in their design: a longer lever for applying maximum force and a shorter one for quick rotation. They are also used for working with fasteners in confined spaces. The high strength characteristics prevent damage to the edges of the fastener. You can also purchase a set of hex keys.